Ukraine has one of the most severe HIV epidemics in Eastern Europe, with an estimated 1.6% of the adult population living with the virus, and an estimated 33% prevalence among drug users in certain regions. Injection drug users (IDUs) account for 36% of new HIV cases in Ukraine. Recent collaborative efforts between international, governmental, and nongovernmental agencies have been made to expand access to substitution therapies and needle/syringe exchange programs in Ukraine. However, systematic and legislative barriers remain for these IDU-specific programs. In addition, while provision of sterile injection equipment is important, and has been shown to reduce new HIV infections among IDUs, such programs alone do not address sexual HIV risk among drug users. Therefore, current HIV prevention efforts among Ukrainian IDUs need to be expanded to include evidence-based strategies that seek to change risk behavior, do not require broad policy changes or political support, and that address the multiple HIV risks drug users face. Efforts to encourage service providers to deliver evidence-based interventions (EBIs) have focused on implementation with fidelity to core elements, or integral components specific to each intervention thought to be responsible for its effectiveness. While over 150 unique interventions have been identified as evidence- based, including 9 that target drug users, in practice they incorporate common factors of effective interventions: cognitive, affective, and behavioral skill-building; tailored, behavior-specific content; and addressing environmental barriers to behavior change. This 4-year, RO1 study seeks to understand how to best promote the use of these evidence-based HIV prevention strategies among Ukrainian NGOs working with drug users. This study combines qualitative and quantitative methods to explore a model of HIV prevention science dissemination and intervention development that 1) promotes the dissemination of common factors of effective behavioral risk reduction interventions (rather than intervention-specific core elements); and 2) enables service providers to develop HIV prevention interventions that reflect their specific organizational contexts. 7-9 NGOs, located in regions of Ukraine with the highest HIV and drug use rates and selected to represent key organizational context criteria (e.g., agency size, target population, experience with HIV prevention), will be taught common factors of effective interventions as the basis for intervention development. Following training, we will use qualitative methods, including interviews with NGO staff, to document the process of intervention development and implementation at each agency. Then, using observations, qualitative interviews, implementation checklists, and risk assessments, we will document intervention implementation to assess inclusion of common factors; aspects of program delivery, including reach and scope; and effectiveness. Primary qualitative analyses will examine the relationship between variations in intervention development, delivery, and effectiveness at each NGO and qualitative data regarding service provider characteristics. We will also compare and contrast agencies' inclusion of common factors and intervention effectiveness with respect to similarities and differences in the context of intervention implementation.